Add speed control to a DIY CNC machine

adding-speed-control-to-diy-cnc

[Jesse Merritt] bought a manual speed controller for his router. It’s used in the CNC mill he build and he figured, why not add the ability for the computer to control the speed.

The speed controller is a $20 unit from Harbor Freight. It comes with an On/Off switch and knob which adjusts the power going to the router. [Jesse] pulled off the knob and milled a gear which takes its place. The second gear is attached to the horn of a hobby servo mounted on the side of the speed controller. The video after the break demonstrates an Arduino driving the servo based on a potentiometer input as well as commands from the CNC controller board he’s using.

Design files for the gears and the Arduino code which drives the servo is available from his Github repository.

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Color-matching powder coat paints

[Zitt] is sharing some methods he’s honed for color-matching powder coat paint. He developed these techniques while restoring a 1982 Star Trek coin-op machine. The image above shows a paddle used for the game. The plate that houses the control was beat up, and he needed to repaint it but wanted to make sure it didn’t look out-of-place with the molded plastic that surrounds it.

He gets his powder paints from Harbor Freight, a favorite depot for hackable goods (like drill motors, or metal carts). Usually these paints would be applied by attracting them to the piece using electrostatic charges. [Zitt's] not doing that, but applying them with a paint sprayer instead.

The first step is to match your color. He’s using an electronic color matching device which gives data to plug into a chart on the web for a color match. Once you’ve got a formula, mix up the powder coat, and then dissolve it into some Methyl Ethyl Ketone. This goes into the spray gun and is applied in an even coat. Before heading into an oven for curing, it’s important to wait for this coat to dry. [Zitt] observed some boiling MEK on a wet test piece that left an undesirable texture on the baked paint after curing. After running a few test pieces he picked the blend that was the best match and then painted all of his restored parts.

Beefing up a cheap drill motor

[Rob] just finished reinforcing a cheap drill motor. He picked up the tool at Harbor Freight and ditched the case. The plastic retaining ring was replaced with a thick metal washer which he machine The washer uses three bolts to attach to the mounting plate that he welded together. We’re not exactly sure what he’s got in mind as he only mentioned that this will be used with a robot. We wouldn’t mind having one of these as a bench motor but there must be hundreds of uses now that it can be attached to just about anything. It seems Harbor Freight has become popular as hacking’s raw material source. The last example we saw of this was a welding table made from a utility cart.

Multi-purpose welding cart

[Todd Harrison] put together a welding cart that has all kinds of tricks built-in. The carcass is a cheap rolling cart that has been reinforced with steel plate and beefier wheels. The top tray can be loaded up with fire brick for oxygen-acetylene welding or with a grate for cutting. That grate lets the slag fall through and into the red-rimmed fire-box below. Finally, there’s a steel plate to the right of the cart that rotates and slides over the top of the unit to prepare it for MIG welding. Todd walks us through his versatile invention in the video after the break. This will nicely augment your other welding hacks.

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Pocket multimeter review

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Reader [Mikey Sklar] told us about a review he wrote covering 3 different models of pocket multimeters. We’re sure that you’ve had the same experiences we have being the go-to-guy or got-to-gal  for all things electrical. For our sort, having a multimeter on hand at all times has become an expectation.

[Mikey] looks at a model from ebay, Harbor Freight, and Radio Shack. Not surprisingly, the ebay offering doesn’t rate too well but does get the job done. We were surprised to read that he picked up the Cen-Tech model for about $10 at Harbor Freight. Although it may no longer be sold there (we haven’t checked) [Mikey] seems pretty happy with it so we’ll be on the lookout during our next tool-buying trip. We’re unfamiliar with the tiny Radio Shack 22-820 but we’ve always been happy with our larger 22-811. The 22-820 allows the probes to be folded up inside of the case cover for a truly pocketable package.

You can never have too many meters at your disposal and we’ll have to keep this article in mind the next time we’re shopping for another. Never used a multimeter before? Take a look at the tutorial [Mikey] linked to over at ladyada.

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